Two weeks ago I published my second historical mystery, Uneasy Spirits, and in the process I was reminded of how confusing it can be to determine the best category and key words I should use on Amazon to describe my book. Since there are several other authors who have been wrestling with the same question in the Historical Fiction Authors Cooperative (HFAC) that I belong to, I decided to write this post on how to use categories and keywords to maximize ebook sales.

For the purpose of this post I am focusing on ebooks on Amazon, in part because that is where I have the most experience, but also because Amazon is definitely ahead of the other ebook stores in its sophisticated approaches to helping readers find books. My understanding of these issues is based on my experience as a self-published author using KDP (Kindle Direct Publishing). Finally, as with much of the publishing process, there is still a lot of conflicting information about how Amazon categories, keywords, and tags work, so some of what I say is more of an educated guess than documented fact.

First some definitions:

Categories: When a book is uploaded into KDP, an author (and, I assume, a traditional publisher) has the opportunity to choose two categories. It used to be that Amazon allowed you to choose five categories, which is why some books have more Kindle Store categories listed at the bottom of their product page. When you, as author, choose a category for your book, you are actually choosing a browsing-path for readers. That browsing-path/category consists of a hierarchy of sub-categories and your book is available for readers to discover under each of the parts of that hierarchy. For example, in the case of my most recent book, Uneasy Spirits, one of the two browsing-path/categories I chose was:

Fiction—Mystery&Thriller—Mystery—Historical

If you browse for Uneasy Spirits in the Kindle store, you will find it in under all four parts of the hierarchy:

Note that each time a reader goes one step further down the hierarchical browsing-path, there are fewer books to browse. For example, as I write this, here are the numbers of books in each of these four areas:

By carefully choosing my category, I make it much more likely that a reader will find my book, since the pool of books is smaller with each step down the path.

The “categories” Amazon offers when you upload your book to KDP are apparently BISAC categories, a book industry standard for subject headings. What is confusing is that the “browsing path” that Amazon generates from your choice is not always the same as the BISAC category you chose. Amazon apparently converts the BISAC categories that you pick into the Amazon browsing-path categories and subcategories that show up in the Kindle store — and the two are not always the same.

To make matters more confusing and frustrating, this conversion process does not always work accurately. You can read more about this on my blog post, “Working Amazon” and on Suzanne Adair’s blog post, which provides a hilarious description of the trouble she had with getting her wonderful new Revolutionary War thriller, Regulated for Murder, in the right category. (Suzanne is a fellow HFAC author.) To complicate issues further, the browsing categories for books and ebooks are not identical, and Amazon creates browsing categories like “newly released” and “best sellers” and “editors’ pick” — some of which are separate from the browsing-path/categories and some of which are available as additional qualifiers to the browsing-paths. Are you lost yet?

Keywords: When you publish your book with KDP, you can choose seven “key-words” in addition to the two categories. These are really key phrases since they can be more than one word. For example I used terms like “Victorian Mystery” and “cozy mystery.” These “key-words” are apparently used by Amazon in its own search engine — along with words in your title and subtitle and product description. This may seem very straightforward, until you get to the next definition—tags.

Tags: These are another kind of key-word or key phrase. They are listed on a book’s product page under the heading “Tag this product” and were designed by Amazon to help customers describe and find products using key words called “tags.” Readers can add tags to a product page and can indicate that an existing tag is useful. It used to be that the “key-words” that authors chose at the time of uploading a book to KDP were automatically displayed as “tags” on the book’s product page, but this evidently no longer happens. Of course, after publication, an author can add tags to a product page just like readers can.

There is contradictory information about how Amazon uses “tags” and “key-words” in its own main search engine, but I believe that “key-words” that the author has assigned to a book are searchable in Kindle store, the but “tags” are not. For example, I did not add the word “clairvoyant” as a “key-word” when I uploaded my book Maids of Misfortune to KDP, but it has been added by customers as a tag on the Maids product page. So, if I go to the Kindle bookstore on the Kindle device (or the main search box on the Amazon website) and search for “clairvoyant,” Maids of Misfortune does not show up in the 100 books that are listed in the search result. So, apparently, Amazon does not include the customer-created “tags” in its Kindle bookstore search (available on the Kindle device) or in the standard search box on the Amazon website.

“Tags” are available for a different kind of searching, though. The “tags” themselves are clickable links. Readers can click on any “Tag” on a product page and find other books that have the same “tag.” For example, if, on the Maids of Misfortune product page, I click on the tag “clairvoyant” (which 19 people checked as useful), the result is 152 books, including Maids of Misfortune. Also, in the “Tag” section of the product page there is a special search box labeled “Search Products Tagged with.” By entering terms in that special search box, you are searching only “tags.” Searching “clairvoyant” using the special tag search box finds those same 152 books. Note that “tags” are typed in by users so you will see misspelled tags!

Why Should an Author Care?

Categories, keywords, and tags can be used to help readers find your books, and these are methods that are generally not available to authors of print books that are sold in brick and mortar stores. As authors of ebooks, we need to learn how readers find books in estores like the Kindle store and use the tools that are available to us to maximize our sales.

When you sell a book to a traditional publisher, who then distributes that book to bookstores, you, as author, really don’t have much to say about how readers find your books. You hope that the bookstores will shelve your book on the right shelf (and that they have separate shelves for your genre) and you hope your publisher can convince the seller (or pay them) to put your book in special places like “newly released” tables, or “best seller” tables, or under “staff recommendations.” Beyond that, there isn’t much authors can do besides cultivating booksellers at conventions and through book signings, hoping this will convince them to feature their books — a time-consuming and expensive proposition. (Although I know one author who always turned their books and books of their friends so that the full cover showed whenever they found them in a bookstore!)

However, self-published authors, by their choice of categories, keywords, and tags, can increase the chances that a reader will find their books in an ebook store. I am going to discuss two strategies an author can use to achieve that end.

The first strategyis to choose a category (browsing path) that ends up with a small number of books at the end of the path.

For example, I could have chosen as one of my two categories, the browsing path of Fiction—Historical Fiction for my newest historical mystery, Uneasy Spirits, which is most certainly a work of historical fiction. However, this would have placed this book in a final pool of over 15,000 books in the Kindle store. Maybe some day I will be such a successful author that I can compete in a pool of that size, but right now as an indie author without a big promotional campaign behind me it would be easy for me to get lost in that pool. Few people are going to scroll down through hundreds if not thousands of books to find mine.

So, I chose to place both of my books, Maids of Misfortune and Uneasy Spirits in the Fiction—Mystery&Thrillers—Mystery—Historical category/browsing-path. Not only does this more accurately define the sub-genre of these two books, but there are fewer than 100 books in this subcategory. It took me six months to reach the top ten books in that subcategory with my first book, Maids of Misfortune, but once I did, my sales went up exponentially. In May 2010, I sold 55 copies of Maids in Kindle and in August, after the book hit the top 10 in this category, I sold 249.

I did a fair number of things to help Maids of Misfortune achieve that top ten status (price changes, reviews, short story, etc.) but I could have done all those things and it still wouldn’t have gotten me into the top 10 in the category of Historical Fiction—it is just too big a pool of books. With the publication of Uneasy Spirits, I had the benefit of now being a better known author, with an already existing fan base, which explains why it took only 24 hours for this book to hit the top ten in the historical mystery subcategory. Even so, as an independent author without a whole publicity machine behind me, I still would not have achieved this within the “Historical Fiction” category.

This strategy (getting your book into the smallest possible pool of books) is also why I chose to put Uneasy Spirits into the browsing path Fiction—Romance—Romantic Suspense (4,800), rather than into the Historical Fiction (15,000 books) or the Historical Romance (8,800 books) subcategories. Again, this was in part because this subcategory accurately describes the book, but also because the pool of books in this subcategory is smaller than in these other two. This is also why, when I had 5 choices of categories when I uploaded Maids of Misfortune, I chose History—United States—state and local—west as one browsing path. I not only figured that people looking for books about the western US would be interested in my book, based as it was on solid historical research, but this was also a pool of less than 500 books, and Maids of Misfortune has been at the top of this list for most of the last year.

The second strategy is to use key-words and tags that will help users find my book in a small pool of potential books.

Let’s take the example of a work of historical fiction that is not a mystery and that, therefore, doesn’t have a lot of options apart from being placed in the historical fiction category with those 15,000 other books in the Kindle store. Here the application of key-words (or tags for people who are doing a tag search) is the appropriate strategy for narrowing the pool to a reasonable level, giving your book a better chance to compete. For example, when I was giving advice to a fellow HFAC author, Elisabeth Storrs, who has written a well-reviewed work of historical fiction,The Wedding Shroud, which has not yet found the readership that it deserves, I investigated what key words she could use.

I discovered that a user who is browsing in the historical fiction subcategory and looking for books about Rome will narrow that list from 15,000 books to 221 books if they put in the search term “Rome.” If they search for “Ancient Rome” they will find a list of just 88 books. And, if they searched for “Early Rome” while browsing in the historical fiction subcategory, they would find just two books.

My recommendation was that she use “Rome” and “Ancient Rome” for two of her seven “key-words” because readers using this browse-then-search strategy would be more likely to find her book in these smaller lists of books that match. This would enable her to compete more successfully in an otherwise broad category. And, of course, these terms more accurately describe the historical fiction she has written!

However, I did not recommend the use of “Early Rome” (although it equally described the period of the book) because it produced such a small pool of books that readers probably wouldn’t return to that search. The other two key-words bring up enough books to make them search terms that readers would be likely to use the next time they were ready to look for a new book.

These two strategies can boost your sales in two additional ways.

First, they will help you get on an Amazon “Top 100 Best Seller List.” Second, they will help ensure that people who find your book will have found books similar to yours — and that improves the chances of your book showing up on the Amazon “Customers who bought this book also bought” recommendation system.

The best-seller lists: Amazon has a computer algorithm that updates the “best-seller lists” in each category and subcategory every hour. While secret, the algorithm evidently takes into consideration “all-time sales, as well as recent sales that are weighted more heavily than older sales…” according to an Amazon spokesperson quoted in this article. Needless to say, no matter how good your sales are in a given hour, or day, your chances of getting into a top 100 best-sellers list and staying there are pretty slim if you are competing against 15,000 other books.

If, however, you are in a group like Horror-Dark Fantasy (227 books), or Science Fiction—Series (169 books), or Fantasy—Authurian (27 books), or Mystery—Historical (73 books), your chances of being ranked in the top 100 in these categories increases (or becomes 100%). Since many customers start their searches for book in the best-seller lists, this heightens your visibility and cachet and increases your sales, which in turn helps you stay on and move up the best seller lists. The increase in sales may, in time, help your book rise in the other categories or key-word searches where your book is listed. Very briefly after Christmas of last year, when my sales were high (700 books in the 3 days after December 25), I actually made the top 100 of the category Mystery—Women sleuths (6,222 books). Heady days!

Customers Who Bought This Item Also Bought: Amazon uses an algorithm that identifies other books that people who have bought your book have bought. You have to have a certain number of sales for this to kick in (Uneasy Spirits had enough Kindle sales so this section appeared within a day—my print edition came out a week later and has had fewer sales, so its product page does not yet have this feature.) In addition, it appears that for a book to appear in this list, a certain number of your customers must have bought the book. For example, nearly 15,000 people have bought Maids of Misfortune, yet there are only 100 books that show up in the “Customers Who Bought” list, and I know that those 15,000 people bought more than 100 books altogether. It also appears that there might be some other limitations; I haven’t seen more than 100 “also-bought” books listed, even for popular books like Amanda Hocking’s ebooks.

You’ll want to do more than just sell enough books to trigger this feature, however. You’ll want to make sure that the books that show up are similar to your book – and you can do that by using the right categories, key-words, and tags. For example, I could certainly have put my books into the category of Romance—Historical, but then the books that would show up in this “Customer who Bought” list would be dominated by books that tend to put the romance before the history and have explicit sexual themes. While there is nothing wrong with these books, a customer who bought my book, based on the expectation it would be like these historical romances, might be very disappointed by the rather chaste nature of my protagonists’ relationship.

Since my books are in the Mystery—Historical category, it is not surprising that the list of books in the “Customer who Bought” feature is filled with historical fiction (usually in the Victorian era) and mysteries. This adds to the chance that the customer who is checking out my book will think, “Hey, I read those books and liked them, I will probably like this one.” And if they buy my book, there is less chance they will be disappointed — thinking, “Where was the sex?” — and give my book a bad review. And finally, it will also mean that my book will show up on “customers who bought” lists for books that are in my sub-genre. You can imagine how pleased I was when I discovered that Maids of Misfortune had started showing up on a “customers who bought” list for Victoria Thompson’s Gaslight Mystery Series! That meant my book was being seen by exactly the readership I want to attract.

In Summary:

As an author, you need to carefully choose categories and key-words when you publish and add your own “tags” after publishing. You need to take into consideration not only what best describes your books but also what will maximize the chances that a reader who is browsing through the Kindle store will find your books. You also want to make sure that readers who find your book are the ones who would be most likely to buy it and enjoy it. Careful uses of categories and key-words and tags can also increase your chance of getting on one of the best-seller lists and showing up on one of the “Customers who bought” lists, which in turn will help boost your sales. Carelessness in using these strategies can condemn even the best work to the backwaters of the Kindle store — undiscovered, unbought, and unread — and that would be a shame.